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A309432
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Number of distinct digits in decimal representation of n^2.
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1
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1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 3, 3, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 4, 4, 3, 3, 4, 4, 2, 3, 3, 3, 4, 4, 4, 3, 3, 3, 4, 4, 3, 4, 4, 4, 4, 4, 3, 4, 3, 4, 3, 4, 3, 3, 4, 3, 4, 3, 3, 4, 3, 4, 4, 4, 4, 3, 3, 3, 4, 4, 3, 3, 4, 3, 4, 3, 4
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OFFSET
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0,5
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LINKS
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EXAMPLE
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a(0) = 1 because 0^2 = 0 has 1 distinct digit (0).
a(5) = 2 because 5^2 = 25 has 2 distinct digits (2, 5).
a(10) = 2 because 10^2 = 100 has 2 distinct digits (0, 1).
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MATHEMATICA
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Array[Count[DigitCount[#^2], _?(# > 0 &)] &, 105, 0] (* Michael De Vlieger, Jun 22 2022 *)
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PROG
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(SageMath)
[len(set(Integer((n^2)).digits(padto=1))) for n in range(25) ]
(PARI) a(n) = if(n==0, 1, #Set(digits(n^2))); \\ Jinyuan Wang, Aug 02 2019, Jun 22 2022 [a(0)=1 corrected by Georg Fischer, Jun 22 2022]
(Python)
def a(n): return len(set(str(n*n)))
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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